1. Field of the Invention
This invention relates to enzymatic dentifrice compositions and, more particularly, to stabilized, aqueous, enzymatic dentifrices which, upon oral application, produce an anti-bacterial and bacteriostatic effect in the oral cavity by activation of the enzyme system within the dentifrice.
2. Related Art
It is disclosed in the prior art that enzymatic anti-bacterial systems, predicated on oxidoreductase enzymes such as glucose oxidase, can be incorporated into oral care products and other products such as powder milk (U.S. Pat. No. 4,617,190) and bandages (U.S. Pat. No. 4,576,817) for producing an anti-bacterial effect in a defined environment.
U.S. Pat. No. 4,150,113 (Hoogendoorn et al., 1979) and U.S. Pat. No. 4,178,362 (Hoogendoorn et al., 1979) disclose, respectively, an enzymatic toothpaste and an enzymatic chewable dentifrice containing glucose oxidase which acts on glucose present in saliva and tooth plaque to produce hydrogen peroxide. The patentees note that oral bacterial, through enzyme systems having SH-GROUPS, effect glycolysis of food products containing sugars and point out that lactoperoxidase, which is present in saliva, provides the means for transferring oxygen from hydrogen peroxide to the oral bacteria resulting in the oxidation of the SH-containing enzymes into inactive disulfide enzymes. It is further disclosed that the dentifrice may be formulated with potassium thiocyanate.
U.S. Pat. No. 4,269,822 (Pellico et al., 1981) discloses an antiseptic dentifrice containing an oxidizable amino acid substrate and an oxidoreductase enzyme specific to such substrate for producing hydrogen peroxide and ammonia upon oral application of the dentifrice, with pre-application stability being maintained by limiting the quantity of any water present in the dentifrice.
U.S. Pat. No. 4,537,764 (Pellico et al., 1985) discloses an enzymatic dentifrice containing Beta-D-Glucose and glucose oxidase for producing hydrogen peroxide upon oral application of the dentifrice, with pre-application stability being maintained by limiting any water in the dentifrice to not more than about 10 wt. % based on the weight of the dentifrice.
U.S. Pat. No. 4,578,365 (Pellico et al., 1986) discloses a di-enzymatic dentifrice which contains, for example, glucose and glucose oxidase for producing hydrogen peroxide upon oral application of the dentifrice and further contains a thiocyanate salt and lactoperoxidase for interacting with hydrogen peroxide to produce a hypothiocyanate (sic) with pre-application stability being maintained by limiting any water in the dentifrice to not more than about 10 wt. % based on the weight of the dentifrice.
U.S. Pat. No. 4,564,519 (Pellico et al., 1986) discloses a di-enzymatic chewable dentifrice which contains, for example, glucose and glucose oxidase for producing hydrogen peroxide upon chewing the dentifrice and further contains a thiocyanate salt and lactoperoxidase for interacting with hydrogen peroxide to produce a hypothiocyanate (sic) bacterial inhibitor, with pre-application stability being maintained by limiting any unbound water in the chewable dentifrice to an amount not more than about 1.0 wt. % and limiting the total water, bound and unbound, to not more than about 10 wt. %.
U.S. Pat. No. 5,176,899 (Montgomery, 1993) discloses an aqueous enzymatic dentifrice which contains, for example, Beta-D-Glucose and glucose oxidase for producing hydrogen peroxide upon oral application of the dentifrice and, optionally, contains a thiocyanate salt and lactoperoxidase for interacting with hydrogen peroxide to produce a hypothiocyanite (OSCN-) bacteriostatic agent, with pre-application stability being maintained by processing and packaging the dentifrice under vacuum conditions or in an inert gas environment so as to limit the level of dissolved oxygen in the dentifrice.
The enzymatic dentifrice compositions described in U.S. Pat. Nos. 4,564,519 and 4,578,265 comprise an enzyme system containing an oxidizable substrate and an oxidoreductase enzyme specific to such substrate for producing hydrogen peroxide upon oral application of the dentifrice with the chemical environment of the oral cavity providing the source of the additional reactant (oxygen) or reactants (oxygen, water) to effect the enzymatic reaction. It is disclosed in these patents that it is essential to limit any water present in the described dentifrices to an amount not more than about 10 wt. % in order to impart maximum stability and shelf life to the compositions since water promotes the oxidation/reduction reaction and is also a reactant in certain enzymatic reactions.
It would, of course, be advantageous to increase the water concentration of the aforesaid enzymatic dentifrice compositions to an amount in excess of 10 wt. % in order to improve the oral application characteristics of the dentifrice, without initiating the enzymatic reaction within the dentifrice package and thereby preserve the package integrity of the product.